Re: [PATCH 3/3] ceph: add support for encrypted snapshot names

[Luís Henriques]

Jeff Layton <jlayton@xxxxxxxxxx> writes:

> On Fri, 2022-03-04 at 16:14 +0000, Luís Henriques wrote:
>> Since filenames in encrypted directories are already encrypted and shown
>> as a base64-encoded string when the directory is locked, snapshot names
>> should show a similar behaviour.
>> 
>> Signed-off-by: Luís Henriques <lhenriques@xxxxxxx>
>> ---
>>  fs/ceph/dir.c   |  9 +++++++++
>>  fs/ceph/inode.c | 13 +++++++++++++
>>  2 files changed, 22 insertions(+)
>> 
>> diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
>> index 934402f5e9e6..17d2f18a1fd1 100644
>> --- a/fs/ceph/dir.c
>> +++ b/fs/ceph/dir.c
>> @@ -1069,6 +1069,15 @@ static int ceph_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
>>  		op = CEPH_MDS_OP_MKSNAP;
>>  		dout("mksnap dir %p snap '%pd' dn %p\n", dir,
>>  		     dentry, dentry);
>> +		/*
>> +		 * Encrypted snapshots require d_revalidate to force a
>> +		 * LOOKUPSNAP to cleanup dcache
>> +		 */
>> +		if (IS_ENCRYPTED(dir)) {
>> +			spin_lock(&dentry->d_lock);
>> +			dentry->d_flags |= DCACHE_NOKEY_NAME;
>> +			spin_unlock(&dentry->d_lock);
>> +		}
>>  	} else if (ceph_snap(dir) == CEPH_NOSNAP) {
>>  		dout("mkdir dir %p dn %p mode 0%ho\n", dir, dentry, mode);
>>  		op = CEPH_MDS_OP_MKDIR;
>> diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
>> index 8b0832271fdf..357335a11384 100644
>> --- a/fs/ceph/inode.c
>> +++ b/fs/ceph/inode.c
>> @@ -182,6 +182,19 @@ struct inode *ceph_get_snapdir(struct inode *parent)
>>  	ci->i_rbytes = 0;
>>  	ci->i_btime = ceph_inode(parent)->i_btime;
>>  
>> +	/* if encrypted, just borrow fscrypt_auth from parent */
>> +	if (IS_ENCRYPTED(parent)) {
>> +		struct ceph_inode_info *pci = ceph_inode(parent);
>> +
>> +		ci->fscrypt_auth = kmemdup(pci->fscrypt_auth,
>> +					   pci->fscrypt_auth_len,
>> +					   GFP_KERNEL);
>> +		if (ci->fscrypt_auth) {
>> +			inode->i_flags |= S_ENCRYPTED;
>> +			ci->fscrypt_auth_len = pci->fscrypt_auth_len;
>> +		} else
>> +			dout("Failed to alloc memory for fscrypt_auth in snapdir\n");
>
> Should we return an error in this case?

Yeah, definitely.  I'll add that and send out v2.  Thanks.

Cheers,
-- 
Luís


>
>> +	}
>>  	if (inode->i_state & I_NEW) {
>>  		inode->i_op = &ceph_snapdir_iops;
>>  		inode->i_fop = &ceph_snapdir_fops;
>
> Seems simple and straightforward at first glance.
> -- 
> Jeff Layton <jlayton@xxxxxxxxxx>